Recently, various cerebrovascular or cardiovascular ischemic diseases have been increased with increasing in population of people of advanced age. At present, as one of medicines for treating these diseases, a calcium channel blocker has been widely used clinically and, therefore, cerebrovascular disorders caused by hypertension are decreased. However, it is said that cardiac ischemic disorders are not decreased, and development of medicines having superior mechanism of activities has been desired.
On the other hand, it has been reported that chlorpromazine having an inhibitory activity to calmodulin which is an intracellular calcium-binding protein is effective for experimental ischemic disorders [G. E. Thomas, S. Levitsky and H. Feinberg, J. Med. Cell Cardiol., 15, 621 (1983); J. I. Dahlager and T. Bilde, Scand. J. Urol Nephrol., 10, 126 (1976); and K. R. Chien, J. Adams, R. G. Plan and J. L. Farber, Am. J. Pathol., 88, 539 (1977)], and it is also said that calmodulin plays an important role in ischemic disorders [S. W. Schaffer, R. S. Roy and J. M. McMcord, Eur. Heart J., 4 (Suppl. H), 81 (1983)]. However, phenothiadines such as chlorpromazine have a strong central depressant activity and, therefore, there is a drawback in the use thereof as a medicine for circulatory system. Therefore, development of a more superior calmodulin inhibitor has been desired.
There are lot of reports relating to imidazo[1,2-a]pyridine derivatives. However, there is few reports about pharmacological activities of compounds wherein a hydrocarbon having a functional group is bound at the 5-position through S, S(O), S(O).sub.2, O or N. For example, European Patent Application P87108189.9 reports such compounds as starting materials for synthesis of cephem compounds. Japanese Patent Liad Open Publication Nos. 277393/1987 and 10792/1988 report them as cephem compounds. EP-A-6614 and DE2820938 report them as hypotensors. However, none of them discloses calmodulin inhibitory activity.